1. Field of the Invention
The present invention relates to a voltage-controlled semiconductor structure, resistor, and manufacturing processes thereof; more particularly, relates to a voltage-controlled semiconductor structure and resistor with high resistivities and manufacturing process thereof.
2. Descriptions of the Related Art
Resistors with high resistivities are widely used in many electrical applications. Currently, there are two main approaches to manufacture resistors with high resistivities. The first approach is to use non-doped polysilicon as the resistor. The highest resistivity of this type of resistors is about 1K ohm/sq. The advantage of this approach is that sizes of resultant resistors are small. However, it has the drawbacks of using additional masks and processes, which costs a lot.
The second approach is to manufacture a resistor with a lightly doped well. The highest resistivity of this type of resistors is about 10K ohm/sq. Since a well with higher doping concentration presents lower resistivity, the resistivity of a resistor can be controlled by using different ion concentrations of the well. However, sizes of resultant resistors are still large.
Both of the two approaches have another common drawback, that is, both resistors cannot adjust the resistivity once the resistors are manufactured.
According to the aforementioned description, it is obvious that both current approaches have critical problems and limit the application of resistor in circuitry. Thus, how to overcome the two problems simultaneously is investigated in this work.